Only barely more than half of the European countries are in EU, and 20 years ago, less than a third was.

Not compared to what democrats want the US federal government to do. EU countries have their own gun laws, separate healthcare, retirement, and unemployment systems, separate housing and labor laws, etc. Separate laws on abortion, same sex marriage, and other social issues.

This is weird, because you're crediting sovereign states for having their "own" national health care, retirement, unemployment, and housing systems, and in the wildest dreams of the Democratic party we wouldn't have a national system for all of these things.

It makes sense if you sort of skim over the idea that Germany, Sweden, and Spain are just "states" in a federation. But obviously, they are not.

@debtinflation was making a pragmatic argument: that modernity renders these granular state lines obsolete. My point is that the EU manages to keep chugging with all these little sovereign states of 5-10 million people managing their own healthcare and retirement systems

Maybe a US state is something legally different than an EU country, maybe not. I would say the two weren’t intended to be different, and whatever trends have produced such a difference were a mistake. Either way, that doesn’t address the practicality question.

Look at the specific examples I provided. European countries closely coordinate their regulation of radio spectrum, air traffic control, nuclear power, and pollution through the EC even if individual countries have separate national regulators on paper.

Sure. Obviously the US does stuff. But that’s very limited compared to what happens (and people want to happen) at the federal level US.